.\" $OpenBSD: CMS_get0_SignerInfos.3,v 1.7 2019/11/02 15:39:46 schwarze Exp $
.\" full merge up to: OpenSSL 83cf7abf May 29 13:07:08 2018 +0100
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.\" This file was written by Dr. Stephen Henson <steve@openssl.org>.
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.Dd $Mdocdate: November 2 2019 $
.Dt CMS_GET0_SIGNERINFOS 3
.Os
.Sh NAME
.Nm CMS_get0_SignerInfos ,
.Nm CMS_SignerInfo_get0_signer_id ,
.Nm CMS_SignerInfo_get0_signature ,
.Nm CMS_SignerInfo_cert_cmp ,
.Nm CMS_SignerInfo_set1_signer_cert
.Nd CMS SignedData signer functions
.Sh SYNOPSIS
.In openssl/cms.h
.Ft STACK_OF(CMS_SignerInfo) *
.Fo CMS_get0_SignerInfos
.Fa "CMS_ContentInfo *cms"
.Fc
.Ft int
.Fo CMS_SignerInfo_get0_signer_id
.Fa "CMS_SignerInfo *si"
.Fa "ASN1_OCTET_STRING **keyid"
.Fa "X509_NAME **issuer"
.Fa "ASN1_INTEGER **sno"
.Fc
.Ft ASN1_OCTET_STRING *
.Fo CMS_SignerInfo_get0_signature
.Fa "CMS_SignerInfo *si"
.Fc
.Ft int
.Fo CMS_SignerInfo_cert_cmp
.Fa "CMS_SignerInfo *si"
.Fa "X509 *certificate"
.Fc
.Ft void
.Fo CMS_SignerInfo_set1_signer_cert
.Fa "CMS_SignerInfo *si"
.Fa "X509 *signer"
.Fc
.Sh DESCRIPTION
.Fn CMS_get0_SignerInfos
returns all the
.Vt SignerInfo
structures associated with the
.Vt SignedData
structure
.Fa cms .
.Pp
.Fn CMS_SignerInfo_get0_signer_id
retrieves the certificate
.Vt SignerIdentifier
associated with the
.Vt SignerInfo
structure
.Fa si .
Either the
.Vt SubjectKeyIdentifier
will be set in
.Fa keyid
or both issuer name and serial number in
.Fa issuer
and
.Fa sno .
.Pp
.Fn CMS_SignerInfo_get0_signature
retrieves the
.Fa signature
field of
.Fa si .
The application program is allowed to modify the data pointed to.
.Pp
.Fn CMS_SignerInfo_cert_cmp
compares the
.Fa certificate
against the signer identifier of
.Fa si .
.Pp
.Fn CMS_SignerInfo_set1_signer_cert
sets the signer certificate of
.Fa si
to
.Fa signer .
.Pp
The main purpose of these functions is to enable an application to
look up signer certificates using any appropriate technique when the
simpler method of
.Xr CMS_verify 3
is not appropriate.
.Pp
In typical usage, an application retrieves all
.Vt CMS_SignerInfo
structures using
.Fn CMS_get0_SignerInfos
and retrieves the identifier information using CMS.
It will then obtain the signer certificate by some unspecified means
(or return and error if it cannot be found) and set it using
.Fn CMS_SignerInfo_set1_signer_cert .
Once all signer certificates have been set,
.Xr CMS_verify 3
can be used.
.Sh RETURN VALUES
.Fn CMS_get0_SignerInfos
returns an internal pointer to all the
.Vt CMS_SignerInfo
structures, or
.Dv NULL
if there are no signers or if
.Fa cms
is not of the type
.Vt SignedData .
.Pp
.Fn CMS_SignerInfo_get0_signer_id
returns 1 for success or 0 for failure.
.Pp
.Fn CMS_SignerInfo_get0_signature
returns an internal pointer to the signature.
.Pp
.Fn CMS_SignerInfo_cert_cmp
returns 0 for a match or non-zero otherwise.
.Pp
Any error can be obtained from
.Xr ERR_get_error 3 .
.Sh SEE ALSO
.Xr CMS_ContentInfo_new 3 ,
.Xr CMS_verify 3
.Sh STANDARDS
RFC 5652: Cryptographic Message Syntax (CMS)
.Bl -dash -compact -offset indent
.It
section 5.1: SignedData Type
.It
section 5.3: SignerInfo Type
.El
.Sh HISTORY
.Fn CMS_get0_SignerInfos ,
.Fn CMS_SignerInfo_get0_signer_id ,
.Fn CMS_SignerInfo_cert_cmp ,
and
.Fn CMS_SignerInfo_set1_signer_cert
first appeared in OpenSSL 0.9.8h and
.Fn CMS_SignerInfo_get0_signature
in OpenSSL 1.0.2.
These functions have been available since
.Ox 6.7 .
